The present invention relates to a semiconductor device that searches an input data string for a predesignated keyword, and also relates to an information processing system that includes the semiconductor device.
As information and communications technology rapidly progresses, there is an increasing need for executing a rapid search for a specific keyword included in data. In the field of security, for example, it is demanded that a character string be extracted at the wire speed of a network.
In an approach that uses a tree search algorithm or a byte shift search algorithm, the need for such a high-speed keyword search is supplied by using a CPU (Central Processing Unit) formed of a plurality of chips or a high-speed CPU. Additionally, in place of such implementation based on software, the use of a semiconductor device including a content-addressable memory (hereinafter may be referred to as the “CAM”) is proposed for implementation.
Disclosed, for instance, in Japanese Unexamined Patent Application Publication No. 2005-018942 is an integrated circuit having a content-addressable memory function that is capable of reducing the load imposed on a control section. Using such an integrated circuit makes it possible to execute a keyword search at an increased speed.